Process for dehydrating potato products

ABSTRACT

A process for dehydrating food products particularly suited to the dehydration of potatoes for use in the preparation of hashbrown potatoes. In accordance with the process of the invention, a food product, e.g. a potato is prepared into separate pieces for drying. The separate pieces are then coated with a dry mixture which includes a separation particulate which maintains separation between adjacent pieces such that the pieces may be more efficiently and effectively hot air dried. The dry mixture also includes ingredients which react with moisture on the food product surface to form an adhesive surface for adhering the dry mixture to the food product. For the preparation of hashbrown potatoes, the dry mixture may include spices, browning ingredients, and patty-binding ingredients. For the preparation of casserole potato dishes, the dry mixture may include spices, dehydrated vegetables and cheeses, and a thickening agent.

FIELD OF THE INVENTION

The present invention relates generally to a dehydration process forfood products particularly suited to dehydrating potatoes for use in thepreparation of hashbrown potatoes.

BACKGROUND OF THE INVENTION

Hashbrown potatoes are typically prepared by forming elongated strandsor shreds of fresh cut potatoes into a patty which is then fried on bothsides. Cutting, shredding, or grating potato pieces into elongatedstrands to form the patties ruptures the potato cells and releases freestarch. This free starch acts as a binder which adheres the individualpotato strands to one another to form a patty and maintain the pattyintact when it is turned to fry both sides.

Another critical feature of hashbrowns is their ability to brown duringthe cooking operation to provide the browned hashbrown coloring on bothsides of the patty. Difficulties in producing the desirable brownedcolor are encountered with potatoes for several months after harvesting,as these potatoes have not yet developed sufficient level of reducingsugars. The browning of the adhesive mixture of potato shreds providesthe flavor and consistency that makes hashbrown potatoes so unique andappealing.

Many attempts have been made in the past to formulate dry or dehydratedhashbrown potato products which duplicate the appearance and flavor offresh-made hashbrowns. U.S. Pat. No. 4,828,856 to Willard, for instance,discloses a method for forming a dehydrated fabricated potato productfor use in the preparation of hashbrown potatoes. Other methods ofmaking similar dry hashbrown products are disclosed in U.S. Pat. Nos.3,634,105 and 3,991,222 to Beck; 3,725,087 to Miller; 3,410,702 toFrank; 3,635,729 to Englar; and 3,650,776 to Tschirgi.

Another form of dehydrated potatoes which can be fried to produce "homefried" potatoes are thin slices. These slices are traditionally used formaking casserole dishes such as scalloped potatoes. Because of thelonger rehydration time required for the thicker potato slices, they arenot as well favored by institutional users for the preparation of homefries. For those who do prefer this shape, the problems of adhesion andoptimum sugar content for browning are the same as described forshredded hashbrown products.

In general, each of the above-noted patents involve dehydrating thepotato by hot air drying. Typically, this involves a processing step inwhich a bed of potatoes (either fresh or reconstituted) are placed in amultistage, conveyer belt dryer and subjected to heated air for a periodof several hours. As is known to those skilled in the art, processingand heating the potatoes diminishes the potato flavor of the finalproduct.

This processing problem is compounded by the use of binder materialswhich may be added during processing of the potatoes to enable formationof stable patties during final cooking. The Englar '729 and Tschirgi'776 patents, for instance, teach the use of free starches which may beapplied in an aqueous solution to the processed potatoes beforecompletion of the drying process. This binder may cause the processedpotatoes to also bind together during the dehydration process. Thisrequires additional heating to heat the bound strands of processedpotato pieces and causes further loss of flavor and additional costs forthe final product. Additionally, with the use of a binder, processingproblems such as clumping and the formation of "blow holes" within apotato bed and adherence of the potatoes to parts of the processingequipment may also occur.

The Frank '702 patent approached this prior art problem by adding apotato binder (made by drying cooked potatoes that had been riced intosmall strands) to conventionally diced or shredded potatoes after theyhad been dried. This process produced a product having a non-homogenousmealy texture. In addition, the previously mentioned processing problemsassociated with prolonged heating for drying the potatoes were stillpresent.

As is apparent, there is a need in the art for a dehydration process inwhich food products can be economically and efficiently dehydrated in aminimum time to reduce flavor loss to a minimum. Additionally, there isa need in the art for an economical processed dehydrated potato productwhich functions in the same manner as a fresh-made hashbrown potatopatty and in which the potato flavor of the final product has not beenlost in processing. The novel and unique dehydration process of thepresent invention satisfies these prior art needs. Moreover, dehydratedhashbrown potatoes processed in accordance with the process of thepresent invention closely resemble the appearance and texture offresh-made hashbrown potatoes and can be easily rehydrated and preparedby an end user.

SUMMARY OF THE INVENTION

In accordance with the present invention, a process for dehydrating foodproducts especially suited for processing dehydrated hashbrown potatoesis disclosed. The process, simply stated, includes the steps of:preparing separate pieces of a food product for dehydration; forming anadhesive surface on the separate pieces of the food product; coating theadhesive surface of the food product with a separation particulate inorder to maintain separation of the food product pieces to form an airpathway for heated air flow between the separated pieces; drying theseparated food product pieces to reduce the moisture content thereof tobelow about 10%. The dehydrated food product pieces can then be packagedas a shelf-stable item and reconstituted by immersion in water for useby an end user in final cooking preparation of potato dishes.

The process of the invention is particularly suited to the formation ofelongated potato strands or shreds which may be rehydrated and cooked ashashbrown potatoes. It is contemplated, however, that potatoes may becut into sizes and shapes and processed for uses other than for theformation of hashbrown, such as slices used for making casserole dishessuch as scalloped potatoes.

In accordance with an illustrative embodiment of the invention forforming hashbrown potatoes, as an initial step, fresh potatoes are firstprepared for dehydration. This typically includes the steps of cutting,shredding, or slicing whole fresh potatoes into elongated shredssuitable for the formation of hashbrown potatoes.

As a next step, the potato shreds are washed to remove free starches,blanched to inactivate enzymes, and then washed again. These steps canbe accomplished by techniques which are known in the art.

An adhesive coating is then formed on the surface of potato shreds. Theadhesive coating may be formed by techniques which are known in the artand may be in the form of pregelatinized starches formed as a film, afilm of polymerized alginate, or simply residual native potato starches.In a preferred form of the invention, the adhesive coating is formed bydry ingredients included in a dry mixture containing the separationparticulates and which react in the presence of moisture on the potatoshreds to form an adhesive surface.

The dry mixture also contains the separation particulate. The separationparticulate is preferably in the form of particulate foodstuff whichadheres to the adhesive surface of the potato shreds. The separationparticulate may be formed of various foodstuff particles such as crushedpotatoes or corn or dehydrated potato particles. The separationparticulate functions to maintain separation of the individual potatoshreds so that the potato shreds may be more efficiently and uniformlyair dried for dehydration.

The particulate-separated potato shreds can be dehydrated byconventional drying, such as with a heated-air conveyer dryer, to amoisture content of about 10%. Separation of the individual potatoshreds by the separation particulate forms spaces or an air pathway forair flow around each potato strand. This facilitates moisture loss fromthe potato shreds to the heated air and, in general, increases theefficiency and uniformity of the drying process. This in turn decreasesthe processing time and lessens loss of potato flavor from the processedpotato pieces. Additionally, the separated potato shreds are notsubjected to clumping and isolated "blow holes" are greatly minimizedwithin a bed of potato shreds being air dried. Moreover, theparticulate-laden potato shreds are heavier and easier to handle thanunprocessed shreds.

In addition to containing particulate foodstuffs which function tomaintain separation of the individual potato shreds and adhesive formingingredients, the dry mixture may also include patty-binding ingredients,browning ingredients, flavorings, preservatives, and antioxidants. Theseadditional ingredients may be formulated to be activated during the highheat of final cooking by an end user. Since these additional ingredientsare adhered to the surface of the potato pieces during processing,separate mixing of spices by an end user is not required.

Many other objects, advantages, and capabilities of the presentinvention will become apparent as the description proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of a process for dehydrating a food product inaccordance with the invention;

FIG. 2 is an enlarged side-elevation view of portions of adjacent foodproduct pieces in which separation of the food product pieces ismaintained in accordance with the invention during drying of the foodproduct pieces;

FIG. 3 is a flow diagram of a process for dehydrating potatoes inaccordance with the invention for use as hashbrown potatoes;

FIG. 4 is a perspective view of a potato strand shaped to provide anincreased surface area for rehydration;

FIG. 5 is a graph of a consumer preference test comparing untreatedpotato shreds, a commercially available Redi-Shred™ product, and treatedpotato shreds processed in accordance with the invention; and

FIG. 6 is a graph showing the drying rate of potato shreds processed inaccordance with invention compared to the drying rate of untreatedshreds.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, a process for dehydrating a food product inaccordance with the present invention is shown. The process broadlystated includes the steps:

preparing a food product for dehydration, including the formation ofseparate pieces of the food product, step 10;

forming an adhesive surface on the separate pieces of food product, step11;

applying a separation particulate to the adhesive surface of theseparate pieces of food product in order to maintain separation and formair pathways between adjacent pieces, step 12; and

drying the separated pieces to remove moisture therefrom, step 14.

The dried food product pieces are then packaged, step 16, and can berehydrated by immersion in water, step 18, prior to final cooking by anend user.

A critical step of the process is step 12 in which a separationparticulate is applied to the surface of the food product in order tomaintain separation of the separate pieces of food product and providean air pathway to allow air flow therebetween during the drying step,step 14. Maintaining separation of the separate food product piecesincreases the efficiency and uniformity of the drying process and allowsthe end product to be more effectively and economically produced.

Prior to application of the separation particulate, step 12, an adhesivesurface must first be formed on the surface of the food product, step11, in order to adhere the separation particulate to the separate piecesof food product. This may be done by techniques which are known in theart. For instance (and as taught in U.S. Pat. No. 3,527,646 to Scheick),a dry powder containing one or more pregelatinized starches may be addedto the separation particulate or to a dry mixture containing theseparation particulate and reacted with a moist surface of the foodproduct pieces to form an adhesive film. Alternately, an adhesivesurface may be formed from the polymerization of alginate and calciumsalt which may be included within the dry mixture and reacted in thepresence of moisture on the food product surface to form an adhesivesurface. Additionally, gums or other mucilaginous substances may also beused to form an adhesive surface. For potato food products, an adhesivesurface may simply be formed by native potato starches formed on thepotato surface by cutting the potato into separate pieces.

Water or moisture may be present on the surface of the food productpieces because during preparation the food product pieces are typicallywashed. The water or moisture must be present in sufficient quantitiesto allow the necessary chemical reaction for forming or polymerizing theadhesive surface to occur. Conversely, there must not be so much wateron the food product pieces that the dry separation particulate mixtureis washed away prior to formation of an adhesive surface.

With reference to FIG. 2, an enlarged cross-section of separate foodproduct pieces 22 having an adhesive surface 28 and a separationparticulate 24 formed thereon are shown. For the purpose ofillustration, the food product pieces 22 and the separation particulate24 are shown with a greatly enlarged size in FIG. 2. In practice, theseparation particulate may be sized in the range of a fine powderpassing through a U.S. 40 mesh sieve (0.42 mm diameter) to particleshaving a diameter of about 1/32 inch or passing through a U.S. 20 meshsieve (0.841 mm). Use of larger particles facilitates the separation ofthe particulate materials from the surfaces of the dried piece duringdrying and handling. As shown in FIG. 2, the separation particulate 24is comprised of a plurality of irregularly shaped individual particles.

The separation particulate 24 functions to maintain separation of theindividual food product pieces 22 to provide an air pathway therebetweensuch that air flow (denoted by arrow 26 in FIG. 2) for drying the foodproduct pieces, step 14, can be more easily directed through and aroundthe individual pieces 22. This increases the rate of heat transfer byconvection and increases the efficiency of drying the food productpieces 22.

The separation particulate 24 may be formed of any food productcompatible particulate foodstuff which remains as a particle solid anddoes not totally dissolve in water from the moist surface of the foodproduct (e.g., salt particles would be ineffective). By way of exampleand not by limitation, some suitable foodstuff particles may be rawgranular starches (potato, corn, or other), crushed or milled potatoparticles, or dehydrated potato particles. Other granular or powderededible particles may also be suitable for this application, provided thematerial functions to adhere to the surface of the potato pieces 22 andmaintain separation of the individual potato pieces 22 to provide an airpathway therebetween.

Once the individual food product pieces 22 have been coated with theseparation particulate 24, the food product pieces 22 can be air dried,step 14, to a moisture content of less than about 10% and preferablyabout 7% for potato products. The food product pieces may be dehydratedby equipment and procedures which are known in the art. As an example,potato pieces may be hot-air dried in a belt conveyer dryer such as aProctor and Schwartz conveyer dryer or the like, which subjects a movingbed of potato pieces to a hot air stream of from about 150° to 225° F.for a period of from about 1 to 4 hours.

The drying or dehydration time of food product pieces processed inaccordance with the invention may be decreased significantly, oversimilar unprocessed food product pieces. Additionally, the separatedfood product pieces tend not to bind together in moist clumps as withconventional uncoated food product pieces, and a rate of throughputthrough a conveyer dryer or the like can be proportionately increased.Moreover, the overall drying process is more uniformly accomplished andthe formation of "blow holes" through a bed of food product pieces isminimized. ("Blow holes" being air conduits through a bed of foodproduct pieces which provide a short circuit for air flow and detractfrom air distribution and the overall efficiency of the drying process.)

After the food product pieces 22 have been dried to a moisture contentof less than about 10%, they can be packaged for storage. In thisdehydrated form, the food product pieces are a shelf stable food productand can be simply packaged in plastic bags or the like.

Prior to final cooking, the food product pieces 22 must be rehydrated byan end user, step 18. For rehydration, the food product pieces 22 may beplaced in cold tap water and allowed to remain overnight for use thefollowing morning, or by placing in hot water for a shorter period. Thefood product pieces, when rehydrated to a ratio of 4 parts rehydratedweight for 1 part dry weight, are returned to approximately the sameoriginal dimension of the food product pieces with a texture that is nottough or leathery, or soft and mushy. The food product pieces can thenbe prepared in conventional dishes.

Embodiment II: Hashbrown Embodiment

Referring now to FIG. 3, a process for producing potato strands orshreds in accordance with the invention and suitable for use ashashbrown potatoes is illustrated. In general, for producing a hashbrownpotato product, the process is the same as previously described for afood product piece but with the addition of a dry mixture containing theseparation particulate as well as browning ingredients for thehashbrowns, and patty-binding ingredients for forming the hashbrownsinto patty form. Flavoring in the form of spices or the like may also beadded. These additional ingredients are mixed with the separationparticulate in a dry mixture and adhere to the adhesive surface of thepotato pieces or shreds as does the separation particulate. Thoseadditional ingredients with non-dissolving character which maintaintheir particulate character in a moist environment may also function asa separation particulate for maintaining separation of the potato shredsduring drying. The patty-binding ingredients and browning ingredients,as will hereinafter be more fully explained, are activated by the hightemperature used for cooking the hashbrowns by an end user. Since theflavorings or spices are adhered to the surface of the potato shredsduring processing, a final end user need not further season or addspices to the mixture, which adds to the convenience of the finalproduct.

With reference to FIG. 3, as a first step of the process, fresh wholepotatoes are peeled, trimmed, and cut into elongated thin strands,shreds, or strips, step 30. A typical strip size may be 1/16 inch indiameter by 2 inches long. By way of example, a suitable slice may be amodel CC Urschel slicer manufactured by URSCHEL Manufacturing Company,Valparaiso, Ind.

Following the preparation step, step 30, the elongated shreds are washedin cold water to remove surface starch, step 32. Following washing, theshreds are blanched by conventional blanching equipment 32. As is knownin the art, blanching heats the potato tissue throughout at time andtemperature conditions high enough to inactivate the enzymes which wouldotherwise cause oxidative darkening of the potato tissue, but notsufficient to soften the tissue enough for normal consumption. Normalblanching conditions range from about 2 to 6 minutes at about 170° F. or190° F. (77° C. to 88° C.). After blanching, the potato shreds mayoptionally be washed again, step 36.

The blanched shreds are then partially de-watered of surface moisture bysuitable means such as draining or drum spinning, step 38. Preferably,excess water is removed from the shreds, but the potato shreds stillcontain enough moisture to enable formation of an adhesive surface fromthe dry mixture including the separation particulate to be added in thefollowing steps.

Following de-watering, a dry mixture containing the separationparticulate, adhesive-forming ingredients, browning and bindingingredients, and spices is mixed with the potato shreds, step 40, sothat the moist exposed surfaces of the shreds are uniformly covered bythe dry mixture. This can be accomplished by metering the dry mixtureonto the shreds as they pass through a rotating coating drum oralternately by other suitable means. The dry particulate is preferablydistributed uniformly on all of the exposed surfaces of the potatoshreds and coats the potato shreds. As previously stated, the drymixture may include the separation particulate, dry spices, andpatty-forming and browning ingredients for the hashbrowns. The drymixture may be on the order of 2 to 8 percent of the total weight of theblanched shreds-dry mix blend. This corresponds to a dry mix content onthe order of 8 to 26 percent of the total weight of finished, driedproduct.

In addition to forming a separated product, the dry mixture adds weightto the potato shreds. This improves the handling of the potato shredsduring processing, helps prevent the formation of "Blow holes" in a bedof potato shreds during the drying step, step 48, and provides a moreformable bulk density for packaging. Further, the dry mixture absorbsand retains extra water during rehydration by the end user which isnecessary for activation of patty forming ingredients, and also producesa less leathery, more moist, natural tasting end product.

For adhering the dry mixture to the surface of the potato shreds, anadhesive coating or film is formed on the surface of the separate potatoshreds, step 42. As previously explained, this may be accomplished byreaction of the adhesive particles which may be included in the drymixture with moisture on the surface of the potato shreds.

An adhesive material for adhering the separation particulate flavorings,spices, browning, and patty-binding ingredients is a gelatinized starch.The most available source is the residual potato starch on the surfacesof the cut potato pieces following blanching and washing. The amount andconsistency of this starch may vary, however, due to the conditions ofthe potatoes, the extent of blanching, and the extent of washingfollowing blanching. While satisfactory adhesion of the particulates hasbeen accomplished using a potato's own residual starch, it is deemedbest to add a dry powdered pregelatinized starch to the dry mixture.Such starches that have been tested successfully include pregelatinizedpotato and corn starch, and modified starches such as Bakasnak Starch(National Starch & Chemical), Ultra-Sperse Starch (National Starch &Chemical), Ultra-Tex Starch (National Starch & Chemical), and Mira-Thik469 Starch (A. E. Staley Manufacturing).

The preferred means of forming an adhesive surface is including in thedry mixture a gel forming reactive mixture of a food-grade polyvalentsalt (cationic), such as calcium or aluminum salt, and anionichydrocolloid, such as algin or low-methoxyl pectin. It is well known inthe art that polyvalent salts react with hydrocolloids containinganionic sites, cross-linking closely aligned hydrocolloids, thus forminginsoluble gels. Calcium salts are preferred cross-linking agents.

Effective levels of polyvalent salt-gelling hydrocolloid are between0.5% to 5%, by weight, of dry mix (all components except food beingdried); 1.5% hydrocolloid being a preferred level. Polyvalent saltlevels in dry mix, sufficient to cause desired gelling, must be adjustedto compliment the polyvalent salt-gelling hydrocolloid level.

Polyvalent salt levels may be in the range of 20% to 80% of the level ofpolyvalent salt-gelling hydrocolloid. When using a preferred polyvalentsalt-gelling hydrocolloid level of 1.5% by weight of dry mix, apolyvalent salt level of 0.54% of dry mix weight has been foundeffective.

With the formation of an adhesive surface, the separation particulatecontained within the dry mixture adheres to the separate potato shredsand maintains separation of the separate potato shreds, step 46.

The separation particulates can be any insoluble food stuff. Dryparticulates, however, which are slow to absorb water, thus maintainingtheir basic physical particulate character in a moist environment aremost suitable for this application. Additionally, the separationparticulate must be compatible to the finished food product.

By way of illustration, and not limitation, examples of suitableseparation particulates are as follows:

Raw crystalline starches including potato starch, corn starch, tapiocastarch, etc. These ingredients serve the dual purpose of separating thepotato shreds during drying and also furnishing adhesive quality to thereconstituted shreds during preparation. For example, at the moment offrying the potato shreds of this invention, water is available at thesurface such that, when the surface temperature of the rehydrated shredsexceeds the gelatinization temperature of the starches (150° F.-170°F.), a starch gel forms, providing an adhesive film for bonding theshreds. This results in patty formation to a degree not possible innormally prepared dried potato shreds, which lack sufficient nativesurface starch for developing well-defined patties. Crispness is alsosignificantly improved.

Other suitable starches include specialty starches, such as AmylomaizeVII Starch (American Maize Co.) and Textaid Starch (National Starch &Chemical). Specialty starches can serve the dual purpose of separatingthe potato shreds during drying and also impart their own respectivequalities of increased crispness, patty forming film, or enhancedinternal texture (mealiness) to the final grilled/cooked product.

It has been found that dehydrated potato products can also be used tocoat the surfaces of the potato shreds. These can include dehydratedmashed potatoes in any convenient form such as potato granules, potatoflakes, potato buds, or crushed dehydrated potato pieces, preferablyground to a size less than about 1/32 of an inch in diameter or to passa 20 mesh (0.0328 inch or 833 mm) sieve. Particles larger than thisfunction well as air pathway forming particulates, but tend to separateduring drying and handling of the finished product. For a moreuniform-appearing finished product, a crushed dehydrated potato passingthrough a 40 mesh (0.0165 inch or 425 mm) screen is preferred.

It has also been found that it is possible to add back previously driedwhole shredded potatoes (add-back shreds) to the treated shreds,including previously dried shreds made by the process of this invention.This can be done after partial de-watering, step 38, of the processwhereat the shreds are still moist. When added at a ratio of between 1%and 20% (basis: dry weight of add-back/wet weight of treated shreds) tothe moist, washed, dewatered treated shreds, before drying, the add-backshreds rapidly absorb water from the treated wet shreds and partiallyhydrate. This creates a textural change to the shreds mixture resultingin significantly more, and larger, air pathways between shreds,resulting in more rapid drying and less shred-to-shred adhesion.Absorption of water by the dry shreds during the first stages of dryingis such that undesirable browning of the add-back shreds is avoided.Products made in this matter have shown drying rates significantlyfaster than the rates achieved with smaller separation particulates. Asan example, it has been found that add-back of 5% dehydrated potatoshreds to wet potato shreds by weight will result in reduction of firststage drying time in a multi-stage drier of about 38% compared to potatoshreds treated with small particulates, and about 60% faster than plain,wet, untreated, conventional potato shreds.

Comminuted, blanched and dewatered potato particles may also be added tothe shreds as a separation particulate. Starting with raw, wholepotatoes, these comminuted potato particles will typically have a moistsurface (i.e., native moisture of whole potatoes). The moist potatoparticles can be added to the potato shreds after dewatering, step 38,and prior to covering the shreds with the dry mixture, step 40. Thisoptional step is shown as step 39 in the flow diagram of FIG. 3.

After treatment with the dry mixture, the potato shreds can then be airdried to a moisture content of less than 10% and preferably about 7%,step 48. A suitable drying arrangement involves depositing the potatoshreds in layers of several inches thick on a two-stage conventionalProctor And Schwartz conveyer dryer. The particulate separated potatoshreds tend not to matt down or stick together, minimizing resistance todrying air, resulting in improved efficiency of the drying process.

The dried potato shreds can then be packaged in plastic bags, sealedcartons, boxes, or other suitable means, step 50. Potatoes processed inthis matter are shelf-stable under normal distribution conditions and donot require refrigeration.

For use by an end user, the potato shreds must be rehydrated by an enduser, step 52. This can be simply accomplished by immersion of thepotato shreds in cold tap water and allowing the shreds to remainovernight for use the following morning, or by placing in hot water fora shorter period. The potato shreds, when rehydrated to a ratio of 4parts rehydrated weight for 1 part dry weight, are returned toapproximately the same original dimension of blanched raw cut potatoeswith a texture that is typical of natural, fresh potato shreds, nottough or leathery, or soft and mushy.

It has been determined that potato shreds formed with relatively largersurface areas can be more efficiently rehydrated during step 52. Onesuch suitable cross-sectional shape for the potato shreds 58 is shown inFIG. 4. As is apparent, a generally cup-shaped (either concave orconvex) cross-sectional configuration provides a relatively largersurface area for water absorption than a generally square, rectangular,or triangular cross-section and thus improves the efficiency of therehydration step, step 52.

The rehydrated potato shreds can then be prepared in conventionaldishes. As previously stated, further seasoning or mixing of spicepackets is not necessary as the dry mixture containing flavorings orspices adheres to the surface of the potato shreds, even though therehydration step, step 52.

The rehydrated hashbrown potatoes can, for instance, be cooked by an enduser by frying on a heated, oiled surface, step 54, or by otherconventional means. During cooking, browning and patty-bindingingredients present in the separation particulate are activated by therelatively high cooking temperatures to produce a browned hashbrownpatty, step 56.

Embodiment III: Slices and Other Dehydrated Potato Pieces

The invention may also be practiced with sliced dehydrated potatoes,normally cut 0.125 inch to 0.0625 inch thick from small potatoestypically called "eliminators". The invention may also be practiced withother sizes and shapes of dehydrated potatoes such as, for example, agenerally square piece measuring 0.750"×0.750"×0.125" or0.25"×1.0"×0.375", etc. Because of the popularity of casseroles preparedfrom dehydrated sliced potatoes for both retail and institutionalfeeding, the discussion will be directed toward the application of theinvention to sliced dehydrated potatoes of about 0.125" thickness.

Thinly sliced potatoes have been used traditionally to prepare bakedcasseroles known as scalloped potatoes or au gratin potatoes bycombining milk, cheese, or other vegetables such as onions and greenpeppers. A wide variety of such dishes are commonly prepared inhouseholds and restaurants. Dried sliced potatoes are also widely usedfor household preparation, mainly for casseroles. For these, a packet ofdried ingredients is furnished together with the dried potatoes forpreparing the casserole. The dry ingredients include the thickeningagents which combine with the water or milk added to the mixture torehydrate the dried potatoes during baking. The dry mixture alsocontains optional ingredients such as seasonings, spices, dehydratedcheeses, and dehydrated vegetables, particularly dried onions.

It has been determined that the process of this invention can be appliedto dried slices and utilized for casserole dishes without the use of theseparately added packet of seasonings, thickeners, and otheringredients. In general, the separation particulate must be formed withparticles with a size which corresponds to the size of the product beingdried. For slices, which are typically larger than potato shredsutilized for hashbrowns, the size of the separation particles must alsobe proportionately larger.

EXAMPLE Shredded Hashbrown Potatoes

Uncoated, plain potato shreds and dry mixture coated, treated shreds(hereinafter abbreviated "Control" and "Treated" products, respectively)were made and dried in a pilot plant as follows:

A bulk quantity of dry mixture (abbreviated hereinafter as "Dry Mix")containing desired air pathway forming separation particulates andhydrocolloid film-forming adhesive components (alginate and calciumsalt), plus flavorings and browning agents, was made as follows:

Ingredient function codes:

F--Flavor

B--Browning during grilling

P--Particulates

A--Dry mix adhesive

D--Dust control

H--Hashbrown patty adhesive

T--Hashbrown texture enhancer

    ______________________________________                                        Num-  Function                       % Dry                                    ber   Code     Ingredient            Mix                                      ______________________________________                                        1     A        Calcium chloride powder                                                                             0.54                                     2     A        Sodium alginate 1.53  1.53                                                    (Protanal SF 120, Protan, Inc.)                                3     B        Dextrose powder       3.06                                     4     B        Nonfat milk powder (-60 mesh                                                                        0.46                                                    screen)                                                        5     D        Glycerol monooleate w/0.08% BHT                                                                     0.92                                                    (or other liquid high-stability lipid)                         6     P, H     Raw potato starch     15.31                                    7     P, H     Raw "Dent" corn starch                                                                              21.43                                    8     P, T     Crushed dried potato dice                                                                           27.56                                                   (87% -40 screen)                                               9     F, P     Onion, granulated     3.83                                     10    F        Sodium chloride       16.84                                    11    F        Potato flavor profile ingredients                                             (Willard U.S. Pat. No. 4,698,230)                                             11a. Toasted potato flakes                                                                          0.61                                                    11b. Sucrose          7.65                                                    11c. Citric acid      0.03                                                    11d. Malic acid       0.02                                                    11e. Potassium chloride                                                                             0.21                                     ______________________________________                                    

Ingredients 11a through 11e are potato flavor profile ingredient asdisclosed in U.S. Pat. No. 4,698,230. Dry mixture ingredients werehomogeneously blended in three parts. Part "A" consisted of blendingsodium chloride, sucrose, citric acid, malic acid, and calcium chloridefor 1 minute in a Leland Model 1000A food mixer, then adding warm,liquefied glycerol monooleate (abbreviated hereafter as "GMO") over 1minute, followed by approximately 8 minutes additional mixing tothoroughly disperse the GMO. Any liquid high-stability fat (oil) willsubstitute for GMO for the purpose of dust control at the same level ofapplication. Part "A" mixture was then transferred to a Marion ModelFPS-2436 Mixer, set at 65-70 revolutions per minute. Part "B" consistingof potato starch and corn starch was added to the Marion Mixer andmixing continued until dust subsided, approximately 5 minutes. Finally,Part "C", consisting of all remaining ingredients, was added to theMarion Mixer and mixing continued until salt analysis indicated ahomogeneous mixture (approximately 17% salt), which required about 10minutes. Blended Dry Mix was stored in poly-lined paper bags until used.

Idaho Russet potatoes were peeled, trimmed, cut to a maximum length of2.50 inches and cut into shreds with an Urschel Model CC cutter equippedwith number 22065 Crinkle blades, offset to produce shreds (instead ofcrinkle slices). Freshly cut potato shreds were thoroughly rinsed incopious amounts of cool tap water to remove native surface starch. Afterrinsing, shreds were dipped in a 200 ppm sulfite solution (sodiummetabisulfite in cool tap water) for approximately 1 minute, thendrained.

Rinsed, sulfite-treated shreds were then blanched in a steam cabinetunder atmospheric steam, twenty pounds at a time, evenly distributedover four trays with screen bottoms, for 31/2 minutes. Blanched shredswere then quickly transferred to a wire basket immersed in a barrel ofcool tap water. Immersed shreds were agitated in the cool water untilcooled below 75° F. then removed from water and drained in the wirebasket, tilted at approximately a 45° angle to facilitate draining.Proper dewatering was achieved when nearly all drip ceased from thebasket, approximately 10 minutes.

Blanched, dewatered potato shreds were divided into two portions: oneportion for Control product (plain, uncoated shreds), and the otherportion for Treated product (to be coated with the Dry Mix). Control andTreated products were stored in plastic pails and covered with plasticfilm to retain moisture until dried.

Control product was prepared by carefully weighing 21 pounds ofblanched, drained shreds and distributing over a tared shallow dryertray to a bed depth of approximately 2.25 inches.

Treated product was prepared as follows: 93.5% blanched, drained shreds;6.5% bulk blend Dry Mix. Coating of shreds with Dry Mix was done in alab seasoning tumbler which consisted of a motorized 55 gallon plasticdrum tilted approximately 15° from horizontal, flights removed, rotatingat 24 revolutions per minute. Dry Mix was added by shaking onto tumblingshreds over 15 seconds and tumbling continued for an additional 60seconds. Initially, the mass of Treated shreds was quite sticky andcohesive. By the end of the mixing the coated shreds had a waxy,slightly cohesive texture with a mealy, fluffed, or "open" appearance.Twenty-one pounds of shreds dough was carefully weighed and spread overa tared dryer tray in the same manner as the Control product above. Beddepth was approximate 2.5 inches. The difference in bed depths indicatesthe open, fluffed state of the Treated product which creates the airpathways which improve drying and reduce sticking.

Bulk densities for Control and Treated products before drying was 31.6and 32.3 pounds per cubic foot, respectively. The tray of Control shredsand tray of Treated shreds were placed in a Proctor And Schwartz Model8078A test dryer for drying (hereinafter abbreviated "P&S dryer").

Drying was conducted in several stages, which is common practice in theart. In Stage #1, air was maintained at 200° F. at a velocity of about400 feet per minute through the trays. Drying was monitored by weighingeach tray of product at approximately 5-minute intervals to determinedrying rates. After weighing, each tray was turned end-for-end and dryershelves exchanged to ensure each product received the same averagedrying environment. Airflow was changed from upflow to downflow after 15minutes. The conditions of Stage #1 drying were maintained for a periodsufficient to dry the shred surfaces so that they could be removed fromStage #1 and dried in a deeper bed in Stage #2 without stickingtogether. This state is normally achieved at a moisture content between45% to 55% and is characterized by a "leatheriness" of individualshreds. More extended drying in Stage #1 can result in productscorching, reduced production, and excessive fuel cost. Transfer fromStage #1 of insufficiently dried shreds can result in matting andsticking during Stage #2 with resultant formation of blow holes andnon-uniformly dried product.

The Treated product dried quickly and uniformly in Stage #1 as a resultof the increased passage of a air between shreds provided by theoccluded particulates. There were no wet, matted-down zones with thisproduct and only a minor amount of slightly over-dried shreds at theperiphery, the latter being unavoidable in stationary batch-type driers.There was no sticking to the tray.

The Control product did not produce an evenly dried bed in Stage #1.Large internal zones of wet, matted shreds were noted, as well asexcessively dry peripheral areas, especially certain areas near holeswhich had been blown through the bed of product as a result of airblockage by the zones of wet shreds. Establishing the end of Zone #1 forControl shreds was made by drying the trays to approximately the samedegree of weight loss. By mixing the under-and over-dried shredsmanually prior to beginning Stage 2, the Control Product could be driedfurther without scorching the over-dried shreds in the same trays. Inevery case, at the end of Stage #1, the Control Product strongly adheredto the tray and was difficult to remove.

At the end of Stage #1 drying, each product was removed from its trayand dumped into a plastic barrel. The shreds were pulled apart, thengently but thoroughly mixed. Samples for moisture analysis were taken.Control shreds were more difficult to pull apart and breakage occurreddue to overly dry shreds. Treated shreds, being more uniformly dried andleathery did not break and parted more easily.

The drying rates for the Control and Treated product are shown below inTable 1, and are based on an initial moisture content of 83% for theblanched, washed shreds.

                  TABLE 1                                                         ______________________________________                                                                 Treated     Treated                                          Control          (as is)     (adjusted)                               Time    Moisture (a)     Moisture    Moisture (b)                             Minutes %       W/S      %    W/S    %     W/S                                ______________________________________                                         0      83.0    4.88     78.0 3.57   83.0  4.88                                6      81.2    4.32     74.0 2.85   79.0  3.76                               10      78.8    3.73     70.9 2.44   75.9  3.15                               15      76.5    3.26     65.0 1.86   70.0  2.33                               21      73.5    2.77     60.3 1.52   65.3  1.88                               25      70.9    2.44     47.8 0.92   52.8  1.12                               30      67.8    2.11     --   --     --    --                                 35      59.2    1.45     --   --     --    --                                 37      53.4    1.15     --   --     --    --                                 ______________________________________                                         (a) Water/solids ratio                                                        (b) Adjusted for 5% solids added to shreds before drying                 

The Treated product contained 5% additional dried ingredients, resultingin a starting moisture content of 78% in contrast to the 83% for theControl product. FIG. 6 shows conventional drying rate curves for theabove data. Plot 4.1 of water/solids ratio (W/S) versus drying timeillustrates the loner drying time required for the Control productcompared to Plot 4.2 for the Treated product. The adjusted drying ratecalculated for the shreds only in the Treated sample is shown as Plot4.3. At about W/S=1.9 to 2.0, the reduction in rate of water removal hasreached the point where movement of water to the surface by capillaryaction stops (FOOD DEHYDRATION, Van Arsdale and Copley, AVI, 1963, p.95).

Upon completion of mixing after Stage #1, both products were placed in asingle deep tray separated by a divider. Bed depths were adjusted to 6inches for each product. Products were finish dried together at 180° F.at an air velocity of about 400 feet per minute through the productbeds. Air flow was reversed between upflow and downflow at 20-minuteintervals. Stage #2 drying time was 40 minutes for both products. Finalmoistures were 7.4% for Control product and 10.0% for Treated product.Dried products were equilibrated in plastic food bags until furtheranalyzed and sensory evaluated.

Several days later, each product was rehydrated by covering dried shredswith 150° F. tap water in a glass beaker (6:1 water to shreds ratio).Temperatures of each beaker of product equilibrated to about 140° F.immediately. Beakers were placed in a temperature controlled water bathat 140° F. and rehydration ratios (wet/dry weights) were monitored bydraining and weighing shreds, until a target rehydration value of 4.0(wet/dry) was achieved. Once optimum rehydration times were established,new batches of Control and Treated products were optimally rehydratedfor grilling and sensory evaluations. A fabricated, dehydratedcommercial hashbrown product, Redi-Shreds™ (Basic American Foods,Blackfoot, Id.) was also optimally rehydrated per package instructionsfor product preference sensory evaluations.

Each of the three products were simultaneously grilled on a commercialgas grill at 375° F. "to color". Effort was made to achieve the samedegree of browning for each product. Each product had a distinct hue ofbrown which could not directly relate one to another.

Data from repetitive grillings by three lab technicians showedRedi-Shreds™ formed significantly stronger patties and were most easy tomanipulate on the grill. Treated product was deemed acceptable inhandling, but the patties were less cohesive that Redi-Shreds™.Untreated shreds were difficult to handle because they were lacking anycohesive property, resulting in an "all-over-the-grill" effect; pattyforming was nil. Thus, Control product was difficult to turn with aspatula.

Grilled products were coded and presented to seven uninformed consumerpanelists for preference evaluation of key characteristics and overallpreference. Treated shreds were preferred over Redi-Shreds™ in allcategories except mouthfeel. Treated shreds outscored Control shreds inall categories, except matched scores in crispness. Treated shreds waspreferred overall. The graphic results of the consumer preference testare illustrated in FIG. 5. The following key applies to the chart ofFIG. 5:

KEY:

A=Visual Appeal

B=Color

C=Crispness

D=Bite of Single Shred

E=Mouthfeel

F=Moistness

G=Oiliness

H=Flavor

I=Overall Preference

In general, panelists responses were based on perception of idealhashbrowns, not judging one product against another.

It has been observed in repetitive lab grillings that Treated shredsretain crispness significantly longer than Redi-Shreds™ or Controlshreds. Treated, grilled shreds retain nearly full crispness up to 30minutes, while Redi-Shreds™ and Control shreds significantly decline incrispness. It has also been noted that if rehydration of Redi-Shreds™ iscontinued beyond the stated conditions, the product becomes soft andmushy.

While the process of the invention has been described with reference topreferred embodiments thereof, as will be apparent to those skilled inthe art, certain changes and modifications can be made without departingfrom the scope of the invention as defined by the following claims.

What is claimed is:
 1. A method of dehydrating a potato productcomprising:a. cutting the potato product into individual pieces; b.forming an adhesive surface on the individual pieces; c. coating theindividual pieces with a separation particulate in order to separate theindividual pieces and form air pathways therebetween for drying; andthen d. drying the separated pieces by directing air around and betweenthe separated pieces.
 2. The method as recited in claim 1 and furthercomprising:forming an adhesive surface on the individual pieces by theaddition of adhesive elements to the separation particulate which reactwith moisture on a surface of the individual pieces for adhering theseparation particulate to the individual pieces.
 3. The method asrecited in claim 2 and wherein:the adhesive elements are contained in adry mixture which also contains the separation particulate.
 4. Themethod as recited in claim 3 wherein the individual pieces are:elongatedpotato shreds suitable for hash brown potatoes, and further comprisingmixing flavorings, browning and patty-binding ingredients with the drymixture.
 5. The method as recited in claim 4 and wherein:the adhesivesurface is formed by a pregelatinized starch included with the drymixture which reacts in the presence of moisture on the potato shreds.6. The method as recited in claim 4 and wherein:the adhesive surface isformed by residual native potato starch on the cut potato shreds.
 7. Themethod as recited in claim 4 and wherein:the adhesive surface is formedfrom the reaction of an anionic hydrocolloid and cationic polyvalentfood-grade salt combined with the separation particulate, in thepresence of moisture on a surface of the potato shreds.
 8. The method asrecited in claim 7 and wherein:the anionic hydrocolloid is selected fromthe group consisting of algin, alginate, sodium alginate, and potassiumalginate.
 9. The method as recited in claim 7 and wherein:the anionichydrocolloid is selected from the group consisting of low-methoxylpectin, sodium pectinate, potassium pectinate, and amidated pectin. 10.The method as recited in claim 4 and wherein:the adhesive surface isformed from the reaction of alginate and calcium salt included withinthe dry mixture in the presence of moisture on the potato shreds. 11.The method as recited in claim 4 and wherein:the separation particulateincludes comminuted potato particles applied to the potato shreds priorto drying.
 12. The method as recited in claim 4 and wherein:previouslydried shredded potatoes are mixed with the potato shreds prior todrying.
 13. The method as recited in claim 1 and wherein:forming anadhesive surface on the individual pieces is by the application ofadhesive forming elements to the individual pieces.
 14. The method asrecited in claim 1 and further comprising:rehydrating the dry separatedpieces by immersion in water.
 15. A method of producing dehydratedpotato pieces comprising:a. cutting potatoes into separate pieces; b.blanching the potato pieces; c. forming an adhesive surface on thepotato pieces; d. applying a separation particulate to the potato piecesin order to maintain separation of the potato pieces and form airpathways therebetween for drying; and then e. drying the separate potatopieces by directing heated air around and between the separate pieces.16. The method as recited in claim 15 and wherein:the adhesive surfaceis formed by residual native potato starch formed from cutting thepotatoes.
 17. The method as recited in claim 15 and wherein:theseparation particulate is included in a dry mixture applied to thepotato pieces.
 18. The method as recited in claim 17 and wherein:the drymixture includes ingredients which react in the presence of moisture onthe potato pieces to form the adhesive surface.
 19. The method asrecited in claim 18 and wherein:the dry mixture includes pregelatinizedstarches which form an adhesive surface on the potato pieces.
 20. Themethod as recited in claim 18 and wherein:the dry mixture is combinedwith a mucilaginous substance which forms an adhesive surface on thepotato pieces.
 21. The method as recited in claim 18 and wherein:the drymixture includes alginate and soluble calcium salt which react to forman adhesive surface.
 22. The method as recited in claim 15 andwherein:the separation particulate includes comminuted potato particles.23. The method as recited in claim 15 and comprising:a. cutting thepotato pieces into elongated shreds suitable for hashbrown potatoes; andb. applying a dry mixture containing the separation particulate,flavorings, browning ingredients, and patty-binding ingredients forforming hashbrown potatoes to the potato shreds.
 24. The method asrecited in claim 23 and wherein:the adhesive surface is formed from thereaction of an anionic hydrocolloid and cationic polyvalent food-gradesalt included in the dry mixture which reacts with moisture on thepotato shreds.
 25. The method as recited in claim 24 and wherein:theanionic hydrocolloid is selected from the group consisting of algin,alginate, sodium alginate, and potassium alginate.
 26. The method asrecited in claim 24 and wherein:the anionic hydrocolloid is selectedfrom the group consisting of low-methoxyl pectin, sodium pectinate,potassium pectinate, and amidated pectin.
 27. The method as recited inclaim 24 and wherein:the polyvalent cationic salt includes anyfood-grade salt.
 28. The method as recited in claim 15 and wherein:a.the potato pieces are sliced and suitable for use in casserole dishes;and b. the separation particulate includes flavorings, dehydratedvegetables, and dehydrated cheeses.
 29. A method of producing adehydrated hashbrown potato product which, when rehydrated and fried,simulates freshly cut hashbrown potatoes, said method comprising:a.peeling, trimming, and cutting potatoes into thin elongated shreds; b.washing the potato shreds; c. blanching the potato shreds; d. applying adry mixture containing a separation particulate and adhesive formingingredients to the potato shreds; e. forming an adhesive surface andadhering the separation particulate to the potato shreds by reaction ofthe adhesive forming ingredients in the dry mixture in the presence ofmoisture on the potato shreds such that the potato shreds are separatedwith air pathways formed between the potato shreds; f. drying theseparated potato shreds, by directing heated air around and between theseparated shreds, to a moisture content of less than about 10%; and theng. packaging the dried potato shreds.
 30. The method as recited in claim29 and wherein:the dry mixture contains flavorings, browning ingredientsand patty-binding ingredients.
 31. The method as recited in claim 29 andwherein:the potato shreds are dried in a multi-stage hot-air conveyerdryer.
 32. The method as recited in claim 29 and wherein:the dry mixtureincludes raw starches.
 33. The method as recited in claim 29 andwherein:the dry mixture includes crushed dehydrated potatoes.
 34. Themethod as recited in claim 33 and further comprising:h. rehydrating thedried potato shreds in water; and i. frying the rehydrated potatoshreds.
 35. The method as recited in claim 29 and wherein:comminutedblanched potato particles are applied to the potato shreds as aseparation particulate.
 36. A method of producing a dehydrated potatopiece which can be rehydrated and cooked as a casserole dishcomprising:a. peeling, trimming, and cutting potatoes into slices; b.washing the potato slices; c. blanching the potato slices; d. applying adry mixture containing a separation particulate, adhesive formingingredients, flavorings, dehydrated cheeses and dehydrated vegetables tothe potato slices; e. forming an adhesive surface on the potato slicesby reaction of the adhesive forming ingredients in the dry mixture inthe presence of moisture on a surface of the potato slices whereby theseparation particulate adheres to the potato slices to maintainseparation of the potato slices and form air pathways between theseparated potato slices; f. drying the separated potato slices, bydirecting heated air around the potato slices and through the airpathways, to a moisture content of less than about 10%; and then g.packaging the potato slices.
 37. A method as recited in claim 36 andwherein:the dry mixture includes a thickening agent which combines withwater used to rehydrate the potato slices during a cooking step.
 38. Amethod as recited in claim 36 and further comprising:h. rehydrating thedried potato slices by immersion in water.
 39. A method of producing adehydrated hashbrown potato product which, when rehydrated and fried,simulates freshly cut hashbrown potatoes, said method comprising:a.peeling, trimming, and cutting potatoes into thin elongated shreds; b.washing the potato shreds; c. blanching and dewatering the potatoshreds; d. applying a dry mixture containing flavorings, a separationparticulate and adhesive forming ingredients to the potato shreds; e.adding to the potato shreds previously dried shredded potatoes; f.forming an adhesive surface and adhering the dried, shredded potatoesand the dry mixture to the potato shreds by reaction of ingredients inthe dry mixture in the presence of moisture on the potato shreds wherebythe elongated shredded potatoes are separated by the separationparticulate and air pathways are formed between the separated shreds fordrying; g. drying the separated potato shreds, by directing heated airaround the shreds and through the air pathways, to a moisture content ofless than about 10%; and then h. packaging the dried potato shreds. 40.The method as recited in claim 39 and wherein:the previously dried,shredded potatoes are added in an amount of between 1% and 20% by weightof the blanched, dewatered potato shreds.
 41. The method as recited inclaim 39 and wherein;the previously dried, shredded potatoes added in anamount of about 5% by weight of the blanched, dewatered potato shreds.42. A method of producing a dehydrated hashbrown potato product which,when rehydrated and fried, simulates freshly cut hashbrown potatoes,said method comprising:a. peeling, trimming, and cutting potatoes intothin elongated shreds; b. washing, blanching, and dewatering the potatoshreds; c. adding comminuted blanched potato particles to the shreds; d.applying a dry mixture containing flavorings and adhesive formingingredients to the potato shreds; e. forming an adhesive surface andadhering the dry mixture and comminuted blanched potato particles to thepotato shreds by reaction of the adhesive forming ingredients in the drymixture in the presence of moisture on the potato shreds whereby thepotato shreds are separated by the comminuted potato particles and airpathways are formed between the shreds for drying; f. drying theseparated potato shreds, by directing heated air around and through theseparated potato shreds, to a moisture content of less than about 10%;and then g. packaging the dried potato shreds.
 43. A method as recitedin claim 42 and wherein:the comminuted blanched potato particles arecomminuted to a size sufficient to allow air flow between the shredsduring drying.
 44. The method as recited in claim 42 and wherein:the drymixture contains a separation particulate.
 45. A product formed by theprocess of claim 42.